Lt. j.g. Jeffrey Grabon launches a global drifter buoy into the Pacific Ocean from the amphibious dock landing ship USS Pearl Harbor (LSD 52) while underway for Pacific Partnership 2013. The buoy, belonging to the UCSD Scripps Institution of Oceanography, is used to measure ocean currents up to 15 meters in depth, sea surface temperatures, and atmospheric pressure.

Submarines provide a country a tremendous advantage because they can operate nearly undetected anywhere in the world. Consequently, the U.S. Navy has been working for a century on ways to track adversary submarines, while simultaneously safeguarding its own presence.

Certainly, technology assists in this high-stakes game of hide-and-seek, but an equally important factor that helps cloak submarines is the ocean environment itself. Water can be clear or opaque, warm or cold, saline or fresh. These subtle differences in the ocean’s conditions at specific sites say a lot about the ease and difficulty of tracking and locating submarines.

The better the U.S. Navy understands the undersea environment, the better Navy operators can “see” what is out there. And if the U.S. Navy can “see” better than its adversaries, it can take advantage of its adversaries’ “blindness” on a tactical level.

The Military Sealift Command oceanographic survey ship USNS Pathfinder (T-AGS 60) conducts a port visit to Veracruz, Mexico. Oceanographers at the Naval Meteorology and Oceanography Command use their understanding of the undersea environment to help fleet operators make tactical decisions.

Every day, the command collects hundreds of ocean observations from in-situ and remotely sensed platforms – satellites, ships, buoys, aircraft, submarines, unmanned vehicles and disseminates the observations to high performance supercomputer centers that quality control and process the data. The resulting high-resolution computer forecast models are used to predict battle space conditions across the fleet in the physical ocean environment.

The Navy’s latest operational tool in this area, the Hybrid Coordinate Ocean Model (HYCOM), is a new global ocean prediction system that drastically improves the understanding and prediction of the ocean environment.

The model is groundbreaking because it uses three different vertical coordinate systems to forecast three very different parts of the ocean. HYCOM captures the shallow, near-shore coastal region with an ocean bottom terrain coordinate system, the well-mixed, dynamic upper layer with a pressure coordinate system and the stratified lower layer of the ocean with a density model.

HYCOM is open source code, which puts the model’s computer code in the public domain and enables programmers and modelers to continue to improve or modify as they identify problems, efficiencies and deficiencies.

As a result, every federal agency with an interest in the ocean is able to use and modify HYCOM to suit unique agency requirements. For instance, the National Weather Service may want to use the model to track oil spills in the Gulf of Mexico while the U.S. Navy monitors sound propagation in the deep ocean.

The model is so complex that it requires large-scale high performance computing and is run operationally at the Navy’s Department of Defense Supercomputing Resource Center at Stennis Space Center, Miss., where the model was developed and tested. Key to HYCOM’s success is the multi-agency team behind its development, which included a detachment from the Naval Research Laboratory, the National Oceanic and Atmospheric Administration, the University of Miami, Florida State University, and the Los Alamos National Laboratory. This close collaboration between researchers, developers and operators ensures that the system gets the best physics and the most accurate observations.

With the high performance computing, HYCOM produces three-dimensional forecasts of temperature, salinity and ocean currents, allowing Navy oceanographers and fleet operators to develop secondary products such as sound propagation for acoustic properties and drift trajectories for floating objects. It has the highest resolution of any ocean forecast model operated by any nation. Simply put, it is the best ocean model in the world.

HYCOM’s greatest contribution to environmental forecasting is still to come, as it has the ability to compliment other environmental models, including those for weather and ice, to better understand and more accurately predict the ocean out to longer timeframes.

The CNO has said our unmatched undersea capability is one of our most important military advantages, but to keep and exploit our superiority, we have to keep investing in training and emerging technology like HYCOM.